Liquid crystal display device and image processing method for same

Abstract

A display device includes a substrate, a plurality of gate lines disposed on the substrate, and which extends in first direction, a plurality of data lines disposed on the substrate, and which extends in a second direction intersecting the first direction, pixels connected to the gate lines and the data lines, a data drive unit which applies data signals to the data lines, a gate drive unit which supplies gate signals to the gate lines, a timing controller which controls the data signals and the gate signals, an image depth analysis unit which receives an image signal, and generates a foreground image signal based on an image depth of the image signal, and a gamma correction unit which generates a gamma-corrected image signal by applying a plurality of gamma curves to the foreground image signal.

What is claimed is: 
     
       1. An image signal processing method comprising:
 receiving an image signal; extracting an image depth of the image signal by analyzing the image signal if the image signal does not include separate image depth information; 
 separating the image signal into a foreground image signal and a background image signal based on the image depth; correcting the foreground image signal based on a plurality of gamma curves; and correcting the background image signal by applying only a single gamma curve to the background image signal. 
 
     
     
       2. The image signal processing method according to  claim 1 , wherein correcting the foreground image signal comprises:
 generating a first gamma-corrected image signal by applying a first gamma curve, having a first gamma value, to a part of the foreground image signal; and 
 generating a second gamma-corrected image signal by applying a second gamma curve, having a second gamma value different from the first gamma value, to a remainder of the foreground image signal. 
 
     
     
       3. The image signal processing method according to  claim 2 , further comprising providing the first gamma-corrected image signal to a first pixel and the second gamma-corrected image signal to a second pixel in a first frame. 
     
     
       4. The image signal processing method according to  claim 3 , wherein the first pixel is provided with a gamma-corrected image signal generated by applying the second gamma curve and the second pixel is provided with a gamma-corrected image signal generated by applying the first gamma curve in a second frame next to the first frame. 
     
     
       5. The image signal processing method according to  claim 2 , wherein:
 correcting the background image signal comprises generating a third gamma-corrected image signal by applying a third gamma curve, having a third gamma value, to the background image signal; and 
 the third gamma value is a value between the first gamma value and the second gamma value. 
 
     
     
       6. The image signal processing method according to  claim 1 , wherein separating the image signal comprises designating a first portion of the image signal as the foreground image signal when a depth of the first portion of the image signal is higher than a reference image depth, and designating a second portion of the image signal as the background image signal when a depth of the second portion of the image signal is lower than the reference image depth. 
     
     
       7. The image signal processing method according to  claim 6 , wherein the reference image depth is a median value of maximum and minimum image depths of the image signal. 
     
     
       8. The image signal processing method according to  claim 6 , wherein the reference image depth is set by a user. 
     
     
       9. The image signal processing method according to  claim 1 , wherein the image depth of the image signal is not extracted by analyzing the image signal if the image signal includes the separate image depth information. 
     
     
       10. A display device comprising:
 a substrate; 
 a plurality of gate lines disposed on the substrate, and which extends in first direction; 
 a plurality of data lines disposed on the substrate, and which extends in a second direction which intersects the first direction; 
 pixels connected to the gate lines and the data lines; 
 a data drive unit which applies data signals to the plurality of data lines; 
 a gate drive unit which supplies gate signals to the plurality of gate lines; 
 a timing controller which controls the data signals and the gate signals; 
 an image depth analyzer which receives an image signal, and generates a foreground image signal based on an image depth of the image signal; and 
 a gamma corrector which generates a gamma-corrected image signal by applying a plurality of gamma curves to the foreground image signal and generates a third gamma-corrected image signal by applying a third gamma curve to the background image signal. 
 
     
     
       11. The display device according to  claim 10 , wherein the image depth analyzer comprises:
 an image depth extractor which extracts the image depth of the image signal; and 
 an image separator which designates a first portion of the image signal as the foreground image signal when an image depth of the first portion of the image signal is higher than a reference image depth and designates a second portion of the image signal as a background image signal when an image depth of the second portion of the image signal is lower than the reference image depth. 
 
     
     
       12. The display device according to  claim 11 , wherein the gamma corrector comprises a composite gamma corrector which generates a first gamma-corrected image signal by applying a first gamma curve to a part of the foreground image signal and generates a second gamma-corrected image signal by applying a second gamma curve to a remainder of the foreground image signal. 
     
     
       13. The display device according to  claim 11 , further comprising a corrected image signal output unit which, in the first frame, receives the first gamma-corrected image signal, the second gamma-corrected image signal, and the third gamma-corrected image signal, and outputs the first gamma-corrected image signal, the second gamma-corrected image signal, and the third gamma-corrected image signal to the data drive unit. 
     
     
       14. The display device according to  claim 13 , wherein in the first frame, the first gamma-corrected image signal corresponds to a data signal to be supplied to a first pixel, and the second gamma-corrected image signal corresponds to a data signal to be supplied to a second pixel, and
 wherein in a second frame next to the first frame, the first pixel is provided with a data signal corresponding to a gamma-corrected image signal generated by applying the second gamma curve and the second pixel is provided with a data signal corresponding to a gamma-corrected image signal generated by applying the first gamma curve. 
 
     
     
       15. The display device according to  claim 13 , wherein a gamma correction value of the third gamma curve of the input image signal is between gamma correction values of the first gamma curve and the second gamma curve. 
     
     
       16. The display device according to  claim 11 , wherein the image depth analyzer receives the reference image depth from a user, and sets the reference image depth. 
     
     
       17. The display device according to  claim 11 , wherein the image depth analyzer determines the reference image depth based on a degree of degradation of image quality by comparing a foreground image, a background image, and an input image. 
     
     
       18. The display device according to  claim 17 , wherein the image depth analyzer analyzes the image quality by applying at least one of a structural similarity index measuring (SSIM) analysis technique, a peak signal-to-noise ratio (PSNR) analysis technique, and a histogram analysis technique. 
     
     
       19. The display device according to  claim 11 , wherein the image depth analyzer constructs an image object by grouping parts of the image signal having similarities in image depths thereof.